[V1, 1/2] i2c: brcmstb: Adding support for CM and DSL SoCs

[Kamal Dasu <kdasu.kdev@gmail.com>]

Broadcoms DSL, CM (cable modem)and STB I2C core implementation have
8 data in/out registers that can transfer 8 bytes or 32 bytes max.
Cable and DSL "Peripheral" i2c cores use single byte per data
register and the STB can use 4 byte per data register transfer.
Adding support to take care of this difference. Accordingly added
the compatible string for SoCs using the "Peripheral" I2C block.

Signed-off-by: Kamal Dasu <kdasu.kdev@gmail.com>
---
 drivers/i2c/busses/i2c-brcmstb.c | 80 ++++++++++++++++++++++++++++------------
 1 file changed, 56 insertions(+), 24 deletions(-)

diff --git a/drivers/i2c/busses/i2c-brcmstb.c b/drivers/i2c/busses/i2c-brcmstb.c
index 8e9637e..3711df1 100644
--- a/drivers/i2c/busses/i2c-brcmstb.c
+++ b/drivers/i2c/busses/i2c-brcmstb.c
@@ -25,13 +25,16 @@
 #include <linux/version.h>
 
 #define N_DATA_REGS					8
-#define N_DATA_BYTES					(N_DATA_REGS * 4)
 
-/* BSC count register field definitions */
-#define BSC_CNT_REG1_MASK				0x0000003f
-#define BSC_CNT_REG1_SHIFT				0
-#define BSC_CNT_REG2_MASK				0x00000fc0
-#define BSC_CNT_REG2_SHIFT				6
+/*
+ * PER_I2C/BSC count register mask depends on 1 byte/4 byte data register
+ * size. Cable modem and DSL SoCs with Peripheral i2c cores use 1 byte per
+ * data register whereas STB SoCs use 4 byte per data register transfer,
+ * account for this difference in total count per transaction and mask to
+ * use.
+ */
+#define BSC_CNT_REG1_MASK(nb)	(nb == 1 ? GENMASK(3, 0) : GENMASK(5, 0))
+#define BSC_CNT_REG1_SHIFT	0
 
 /* BSC CTL register field definitions */
 #define BSC_CTL_REG_DTF_MASK				0x00000003
@@ -41,7 +44,7 @@
 #define BSC_CTL_REG_INT_EN_SHIFT			6
 #define BSC_CTL_REG_DIV_CLK_MASK			0x00000080
 
-/* BSC_IIC_ENABLE r/w enable and interrupt field defintions */
+/* BSC_IIC_ENABLE r/w enable and interrupt field definitions */
 #define BSC_IIC_EN_RESTART_MASK				0x00000040
 #define BSC_IIC_EN_NOSTART_MASK				0x00000020
 #define BSC_IIC_EN_NOSTOP_MASK				0x00000010
@@ -169,6 +172,7 @@ struct brcmstb_i2c_dev {
 	struct completion done;
 	bool is_suspended;
 	u32 clk_freq_hz;
+	int data_regsz;
 };
 
 /* register accessors for both be and le cpu arch */
@@ -186,6 +190,16 @@ struct brcmstb_i2c_dev {
 #define bsc_writel(_dev, _val, _reg)					\
 	__bsc_writel(_val, _dev->base + offsetof(struct bsc_regs, _reg))
 
+static inline int brcmstb_i2c_get_xfersz(struct brcmstb_i2c_dev *dev)
+{
+	return (N_DATA_REGS * dev->data_regsz);
+}
+
+static inline int brcmstb_i2c_get_data_regsz(struct brcmstb_i2c_dev *dev)
+{
+	return dev->data_regsz;
+}
+
 static void brcmstb_i2c_enable_disable_irq(struct brcmstb_i2c_dev *dev,
 					   bool int_en)
 {
@@ -323,14 +337,16 @@ static int brcmstb_i2c_xfer_bsc_data(struct brcmstb_i2c_dev *dev,
 				     u8 *buf, unsigned int len,
 				     struct i2c_msg *pmsg)
 {
-	int cnt, byte, rc;
+	int cnt, byte, i, rc;
 	enum bsc_xfer_cmd cmd;
 	u32 ctl_reg;
 	struct bsc_regs *pi2creg = dev->bsc_regmap;
 	int no_ack = pmsg->flags & I2C_M_IGNORE_NAK;
+	int data_regsz = brcmstb_i2c_get_data_regsz(dev);
+	int xfersz = brcmstb_i2c_get_xfersz(dev);
 
 	/* see if the transaction needs to check NACK conditions */
-	if (no_ack || len <= N_DATA_BYTES) {
+	if (no_ack || len <= xfersz) {
 		cmd = (pmsg->flags & I2C_M_RD) ? CMD_RD_NOACK
 			: CMD_WR_NOACK;
 		pi2creg->ctlhi_reg |= BSC_CTLHI_REG_IGNORE_ACK_MASK;
@@ -348,20 +364,22 @@ static int brcmstb_i2c_xfer_bsc_data(struct brcmstb_i2c_dev *dev,
 		pi2creg->ctl_reg = ctl_reg | DTF_RD_MASK;
 
 	/* set the read/write length */
-	bsc_writel(dev, BSC_CNT_REG1_MASK & (len << BSC_CNT_REG1_SHIFT),
-		   cnt_reg);
+	bsc_writel(dev, BSC_CNT_REG1_MASK(data_regsz) &
+		   (len << BSC_CNT_REG1_SHIFT), cnt_reg);
 
 	/* Write data into data_in register */
+
 	if (cmd == CMD_WR || cmd == CMD_WR_NOACK) {
-		for (cnt = 0; cnt < len; cnt += 4) {
+		for (cnt = 0, i = 0; cnt < len; cnt += data_regsz, i++) {
 			u32 word = 0;
 
-			for (byte = 0; byte < 4; byte++) {
-				word >>= 8;
+			for (byte = 0; byte < data_regsz; byte++) {
+				word >>= BITS_PER_BYTE;
 				if ((cnt + byte) < len)
-					word |= buf[cnt + byte] << 24;
+					word |= buf[cnt + byte] <<
+					(BITS_PER_BYTE * (data_regsz - 1));
 			}
-			bsc_writel(dev, word, data_in[cnt >> 2]);
+			bsc_writel(dev, word, data_in[i]);
 		}
 	}
 
@@ -373,14 +391,15 @@ static int brcmstb_i2c_xfer_bsc_data(struct brcmstb_i2c_dev *dev,
 		return rc;
 	}
 
+	/* Read data from data_out register */
 	if (cmd == CMD_RD || cmd == CMD_RD_NOACK) {
-		for (cnt = 0; cnt < len; cnt += 4) {
-			u32 data = bsc_readl(dev, data_out[cnt >> 2]);
+		for (cnt = 0, i = 0; cnt < len; cnt += data_regsz, i++) {
+			u32 data = bsc_readl(dev, data_out[i]);
 
-			for (byte = 0; byte < 4 &&
+			for (byte = 0; byte < data_regsz &&
 				     (byte + cnt) < len; byte++) {
 				buf[cnt + byte] = data & 0xff;
-				data >>= 8;
+				data >>= BITS_PER_BYTE;
 			}
 		}
 	}
@@ -448,6 +467,7 @@ static int brcmstb_i2c_xfer(struct i2c_adapter *adapter,
 	int bytes_to_xfer;
 	u8 *tmp_buf;
 	int len = 0;
+	int xfersz = brcmstb_i2c_get_xfersz(dev);
 
 	if (dev->is_suspended)
 		return -EBUSY;
@@ -482,9 +502,9 @@ static int brcmstb_i2c_xfer(struct i2c_adapter *adapter,
 
 		/* Perform data transfer */
 		while (len) {
-			bytes_to_xfer = min(len, N_DATA_BYTES);
+			bytes_to_xfer = min(len, xfersz);
 
-			if (len <= N_DATA_BYTES && i == (num - 1))
+			if (len <= xfersz && i == (num - 1))
 				brcmstb_set_i2c_start_stop(dev,
 							   ~(COND_START_STOP));
 
@@ -542,8 +562,12 @@ static void brcmstb_i2c_set_bus_speed(struct brcmstb_i2c_dev *dev)
 
 static void brcmstb_i2c_set_bsc_reg_defaults(struct brcmstb_i2c_dev *dev)
 {
-	/* 4 byte data register */
-	dev->bsc_regmap->ctlhi_reg = BSC_CTLHI_REG_DATAREG_SIZE_MASK;
+	if (brcmstb_i2c_get_data_regsz(dev) == sizeof(u32))
+		/* set 4 byte data in/out xfers  */
+		dev->bsc_regmap->ctlhi_reg = BSC_CTLHI_REG_DATAREG_SIZE_MASK;
+	else
+		dev->bsc_regmap->ctlhi_reg &= ~BSC_CTLHI_REG_DATAREG_SIZE_MASK;
+
 	bsc_writel(dev, dev->bsc_regmap->ctlhi_reg, ctlhi_reg);
 	/* set bus speed */
 	brcmstb_i2c_set_bus_speed(dev);
@@ -608,6 +632,13 @@ static int brcmstb_i2c_probe(struct platform_device *pdev)
 		dev->clk_freq_hz = bsc_clk[0].hz;
 	}
 
+	/* set the data in/out register size for compatible SoCs */
+	if (of_device_is_compatible(dev->device->of_node,
+				    "brcmstb,brcmper-i2c"))
+		dev->data_regsz = sizeof(u8);
+	else
+		dev->data_regsz = sizeof(u32);
+
 	brcmstb_i2c_set_bsc_reg_defaults(dev);
 
 	/* Add the i2c adapter */
@@ -674,6 +705,7 @@ static SIMPLE_DEV_PM_OPS(brcmstb_i2c_pm, brcmstb_i2c_suspend,
 
 static const struct of_device_id brcmstb_i2c_of_match[] = {
 	{.compatible = "brcm,brcmstb-i2c"},
+	{.compatible = "brcm,brcmper-i2c"},
 	{},
 };
 MODULE_DEVICE_TABLE(of, brcmstb_i2c_of_match);
-- 
2.3.2